1. Field of the Invention
This invention relates to a gate valve, and, more particularly, to gate valves formed with spaced parallel housing plates with axially aligned apertures for constituting a housing, with sleeves removably coupled to the housing plates defining an annular space therebetween, and with an elongated gate plate having an apertured section and an imperforate section positioned in sliding contact with the sleeves and reciprocable to open and close the valve.
2. Description of the Background Art
In the field of fluid handling, it is common practice to insert a valve along lengths of pipes so that the flow of fluids through the pipes may be selectively interrupted or continued at the control of an operator. One common type of valve is that formed with an apertured housing and an imperforate, reciprocable plate or gate having a knife edge. Such valves are commonly called knife valves. The gate with the knife edge is slidably reciprocable into and out of the housing. The housing is coupled to adjacent ends of coupled pipes. When the gate is retracted out of the housing, the valve is open to allow the flow of fluid through the pipes and housing. When the gate is advanced into the housing, the apertures of the housing are blocked by the gate and the flow of fluid through the pipes and housing is precluded. The housing halves on opposite sides of the gate are secured on their axially exterior faces to the pipes while their interior faces are provided with elastomeric sleeves in tight compressive contact when the gate is retracted to ensure the flow of fluid therethrough without leakage. The advancement of the knife edge of the gate to terminate the flow of fluids causes even further compression of the sleeve. Movement of the gate is effected through an actuator thereabove.
In view of the large number of fixed and movable parts to use, operate, maintain and repair, a typical knife valve is expensive and requires constant attention by a skilled operator. Additionally, the movement of the knife edge of the gate may cause damage to the contacted seal members of the housing upon movement of the gate to the closed position. Further, the relationship of the housing, gate and actuator are generally such that the gate may only be replaced from the actuator side of the housing and only after disassembling the actuator from the housing. Such an arrangement is often disruptive to the use of the pipes and inconvenient to its operator. In addition, sealing sleeves in constant high and varying compression as found in knife valves have decreased lives. Lastly, gate and housing members of knife valves are expensive, requiring casting or machining as compared to the use of less expensive sheet metal cut to size.
A typical knife valve is disclosed in U.S. Pat. No. 4,257,447 to Clarkson. Such knife valve suffers from all of the shortcomings as enumerated above. Further, as is typical in many knife valves, the gate slides against metal sealing rings which cause excessive wear of the gate as well as of the sealing rings thereby necessitating expensive repairs and resulting in costly down time. Such metal to metal contact also accelerates corrosion. In addition, the sealing sleeves of Clarkson are of a multi-piece construction which increases cost, complexity of repair, and enlargement of the stock of repair parts.
Modified knife valves of the Clarkson type have also been used with an elongated gate having both imperforate and apertured sections. While such modified knife valves have extended utility over those of the type described in the Clarkson patent, most of the above-enumerated shortcomings continued, particularly the sleeve being under heavy compression at all times, as well as the wearing on metal to metal surfaces.
An optimum assembly would be something new which combines the benefits of the prior practices without their shortcomings, i.e., an assembly which provides for the efficient gating of pipes; convenient and simplified operation, repair, replacement, etc.; reliable operation over an extended life of valves and their component elements; and economical cost to manufacture, maintain, repair, use and operate.
As illustrated by a great number of prior patents as well as commercial devices, efforts are continuously being made in an attempt to improve valves whereby pipes may convey fluids more efficiently, conveniently, reliably and economically. None of these previous efforts, however, provides the benefits attendant with the present invention. Additionally, prior valves do not suggest the present inventive combination of component elements arranged and configured as disclosed and claimed herein. The present invention achieves its intended purposes, objectives and advantages over the prior art devices through a new, useful and unobvious combination of component elements, with the use of a minimum number of functioning parts, at a reduced cost to manufacture, and by employing only readily available materials.
Therefore, it is an object of this invention to provide improved gate valves formed of spaced parallel housing plates with axially aligned apertures for constituting a housing, with sleeves removably coupled thereto defining an annular space therebetween and with an elongated gate plate having an apertured section and an imperforate section positionable in sliding contact with the sleeves and reciprocable to open and close the valve.
It is another object of this invention to relieve the constant and varying compressive forces on sealing sleeves of a knife valve by supporting such sealing sleeves at a predetermined distance from each other so that a gate plate with no knife edge, and of a thicknesses only slightly greater than the predetermined distance may be used.
It is a further object of this invention to eliminate metal to metal sliding contacts between gate plates and their supporting housings.
It is yet a further object of the present invention to remove and replace gate plates of gate valves without disturbing any other component of the gate valve assembly or associated pipes.
Lastly, it is an object of the present invention to provide an improved gate valve which is more efficient, convenient, reliable, economical and easy to operate and repair.
The foregoing has outlined some of the more pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiments in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.